Saw chains for motor-driven chain saws comprise center drive links with right and left cutting links alternating on the longitudinal sides of the drive links as well as side links likewise alternating on the longitudinal sides of the drive links. All links are pivotally connected one to the other, for example, with pivot bolts. A spacing gap is disposed between the cutting links and the corresponding next adjacent drive links and a spacing gap is provided between the side links and the drive links so that lubricating oil can reach the pivot locations and the rivets. This provides lubrication for the saw chain and therefore maintains the pivoting action and reduces wear. The lubricating oil is absolutely necessary.
Published German patent application 1,453,167 discloses a groove-shaped oil supply in the side flanks of the chain links in order to improve this important lubrication of the pivot locations. Annular grooves are suggested in French patent publication 1,390,071 to improve the oil feed to the saw chain rivets.
In practice, it has been known and accepted for decades that not only lubricating oil enters through the necessary oil supply gap between mutually adjacent chain links but also the most varied dirt particles and that these particles can reach the rivets and cause increased wear at the bearing locations of the chain links and therefore cause premature wear. The dirt particles are unavoidably present when working with the chain saw and include the finest grains of sand, metal particles and the like. This is especially disadvantageous for saw chains having small parts as is the case for motor chain saws made for home use. In these chain saws, the chain links are precision small parts having a longitudinal length of approximately 10 to 20 mm and having rivet connections of approximately 9.525 mm.